废铁屑强化污泥厌氧消化产甲烷可行性分析

有关全球气候变化的《巴黎协定》落槌,预示着污水处理追求碳中和运行的时代已经来临.碳中和狭义理解即能源自给自足,这就要求污水处理厂应最大程度转化污水中有机物或产生的剩余污泥所蕴含的有机能源,并将其生成可再生能源——甲烷.然而,剩余污泥能源转化率较低一直都是限制厌氧消化技术广为应用的瓶颈.在污泥预处理技术之外,向厌氧消化系统中投加废铁屑强化甲烷生产有望成为另一个提高能源转化率的突破口,继而实现"以废促能、变废为宝"的目的.本综述从铁腐蚀析氢现象入手,在描述铁腐蚀析氢原理、析出H2对产CH4过程影响的基础上,对铁在厌氧系统ORP减少方面的作用、对厌氧微生物生理、生化特性的影响、对涉及微生物酶活的影响等进行了全面的介绍.最后,还通过生命周期评估(LCA)评价了基于废铁屑的污泥厌氧消化技术对环境的影响及经济合理性.

Feasibility analysis of enhancing anaerobic digestion for methane production by waste iron scrap

The Paris Agreement concerning the global climate change implies that the operational era of wastewater treatment plants (WWTPs) towards carbon neutrality is coming. The narrow definition of carbon neutrality for WWTPs is regarded as energy self-sufficiency, which requires converting organic substance/excess sludge to renewable energy:methane (CH₄). However, the low energy conversion efficiency of excess sludge has been being a bottleneck of anaerobic digestion. Beyond pretreatment for excess sludge, adding waste iron scrap (WIS) to anaerobic digestion system is expected to become another breakthrough for enhancing the energy conversion efficiency, so that the purpose of "waste enhancing energy and waste becoming resource" could be realized. In this article, hydrogen evolution from iron corrosion and its effects on CH₄ production is firstly reviewed; then the roles of iron in reducing ORP, affecting biochemical/physiological characteristics of microorganisms and their enzyme activities are elaborated; finally, the environmental and economic issues of WIS-based anaerobic digestion are evaluated using the method of life cycle assessment (LCA).